cheat.sheets:jq
# jq
# A lightweight and flexible command-line JSON processor.
# Output a JSON file, in pretty-print format:
jq
# Output all elements from arrays
# (or all key-value pairs from objects) in a JSON file:
jq .[]
# Read JSON objects from a file into an array, and output it
# (inverse of jq .[]):
jq --slurp
# Output the first element in a JSON file:
jq .[0]
# Output the value of a given key of the first element in a JSON file:
jq .[0].key_name
# Output the value of a given key of each element in a JSON file:
jq 'map(.key_name)'
#
# [ { foo: 1 }, { foo: 2 } ]
# => [1, 2]
# Extract as stream of values instead of a list
jq '.[] | .foo'
#
# [ { "foo": 1 }, { "foo": 2 } ]
# => 1, 2
# Slicing
jq '.[1:2]'
#
# [ { "foo": 1 }, { "foo": 2 } ]
# => { "foo": 2 }
# Dictionary subset shorthand
jq 'map({ a, b })'
#
# [ { "a": 1, "b": 2, "c": 3 }, ...]
# => [ { "a": 1, "b": 2 }, ...]
# Converting arbitrary data to json
jq -r '(map(keys) | add | unique | sort) as $cols \
| .[] as $row | $cols | map($row[.]) | @csv'
#
# [ { "foo": 1, "bar": 2}, { "foo": 3, "baz": 4}]
#
# => 2,,1
# ,4,3
# Filter a list of objects
jq 'map(select(.name == "foo"))'
#
# [ { "name": "foo" }, { "name": "bar" } ]
# => [ { "name": "foo" } ]
#
# ## mapping and transforming ##
#
# Add + 1 to all items
jq 'map(.+1)'
# Delete 2 items
jq 'del(.[1, 2])'
# Concatenate arrays
jq 'add'
# Flatten an array
jq 'flatten'
#
# [[1], [2]]
# => [1, 2]
# Create a range of numbers
jq '[range(2;4)]'
# Display the type of each item
jq 'map(type)'
# Sort an array of basic type
jq 'sort'
#
# [3, 2, 1]
# => [1, 2, 3]
# Sort an array of objects
jq 'sort_by(.foo)'
# Sort lines of a file
jq --slurp '. | sort | .[]'
# Group by a key - opposite to flatten
jq 'group_by(.foo)'
# Minimum value of an array
jq 'min'
# See also min, max, min_by(path_exp), max_by(path_exp)
# Remove duplicates
jq 'unique'
# or
jq 'unique_by(.foo)'
# or
jq 'unique_by(length)'
#
# [1, 1, 2, 1]
# => [1, 2]
# Reverse an array
jq 'reverse'
#
# ## jq in shell scripts ##
#
# URL Encode something
date | jq -sRr @uri
# Thu%2021%20May%202020%2012%3A40%3A40%20PM%20CEST%0A
# To create proper JSON from a shell script and properly escape variables:
jq -n --arg foobaz "$FOOBAZ" '{"foobaz":$foobaz}'
# To fill environment variables from JSON object keys
# (e.g. $FOO from jq query ".foo")
export $(jq -r '@sh "FOO=\(.foo) BAZ=\(.baz)"')
#
# ## Input/output formats ##
#
# Parsing json
jq 'with_entries(.value |= fromjson)' --sort-keys
#
# { "b": "{}", "a": "{}" }
# => { "a": {}, "b": {} }
# Serializing json
#
jq 'with_entries(.value |= tojson)' --sort-keys
#
# { "a": {}, "b": {} }
# => { "a": "{}", "b": "{}" }
# Converting to csv
jq '.[] | [.foo, .bar] | @csv' -r
#
# [{ "foo": 1, "bar": 2, "baz":3 }]
# => 1,2
cheat:jq
# To pretty print the json:
jq "." < filename.json
# To access the value at key "foo":
jq '.foo'
# To access first list item:
jq '.[0]'
# to slice and dice:
jq '.[2:4]'
jq '.[:3]'
jq '.[-2:]'
# to extract all keys from json:
jq keys
# to sort by a key:
jq '.foo | sort_by(.bar)'
# to count elements:
jq '.foo | length'
# print only selected fields:
jq '.foo[] | {field_1,field_2}'
# print selected fields as text instead of json:
jq '.foo[] | {field_1,field_2} | join(" ")'
# only print records where given field matches a value
jq '.foo[] | select(.field_1 == "value_1")'
tldr:jq
# jq
# A command-line JSON processor that uses a domain-specific language.
# More information: <https://stedolan.github.io/jq/manual/>.
# Execute a specific expression (print a colored and formatted json):
cat path/to/file.json | jq '.'
# Execute a specific script:
cat path/to/file.json | jq --from-file path/to/script.jq
# Pass specific arguments:
cat path/to/file.json | jq --arg "name1" "value1" --arg "name2" "value2" ... '. + $ARGS.named'
# Print specific keys:
cat path/to/file.json | jq '.key1, .key2, ...'
# Print specific array items:
cat path/to/file.json | jq '.[index1], .[index2], ...'
# Print all array items/object keys:
cat path/to/file.json | jq '.[]'
# Add/remove specific keys:
cat path/to/file.json | jq '. +|- {"key1": "value1", "key2": "value2", ...}'
$
cheat.sh